Load driving system

Abstract

A load driving system uses two gear trains with different characteristics. The load driving system includes a motor, a first pinion gear which is installed on the output shaft of the motor, a first gear train transmitting the rotation from the first pinion gear to a load, a second pinion gear separate from the first pinion gear which is also mounted on the motor output shaft, a second gear train having different characteristics from the first gear train and transmitting the rotation from the second pinion gear to the load, a connector for connecting the first gear train to the load while separating the second gear train from the load and for connecting the second gear train to the load while separating the first gear train from the load, and a controller for selecting one of the first and second gear trains based on a battery discharge level. The first and second gear trains are selected by selecting a rotational direction of the motor.

What is claimed is: 
     
       1. A load driving system, comprising: a motor;   a first pinion gear mounted on a shaft of the motor;   a first gear train of a plurality of gear trains coupling the first pinion gear with a load;   a second pinion gear mounted on the shaft of the motor;   a second gear train of the plurality of gear trains coupling the second pinion gear with the load;   connecting means for connecting one of the plurality of gear trains to the load; and   control means for selecting one of the plurality of gear trains.   
     
     
       2. The load driving system of claim 1, wherein the motor rotates in a first direction and a second direction. 
     
     
       3. The load driving system of claim 1, wherein the first gear train has high transmission efficiency and the second gear train has low rotational noise. 
     
     
       4. The load driving system of claim 2, wherein the connecting means connects the first gear train to the load when the motor rotates in a first direction and the second gear train to the load when the motor rotates in a second direction. 
     
     
       5. The load driving system of claim 4, wherein the connecting means separates the second gear train from the load when the first gear is connected to the load and separates the first gear train from the load when the second gear is connected to the load. 
     
     
       6. The load driving system of claim 4, wherein the control means selects the first gear train by rotating the motor in the first direction and the second gear train by rotating the motor in the second direction. 
     
     
       7. The load driving system of claim 6, further comprising a battery for supplying power to drive the motor, wherein the control means selects the first gear train when a battery discharge level is at least a predetermined value and the second gear train when the battery discharge level is below the predetermined value. 
     
     
       8. The load driving system of claim 6, wherein the control means selects the first gear train when a temperature is below a predetermined temperature value. 
     
     
       9. The load driving system of claim 6, wherein the control means selects the second gear train when an ambient noise level is below a predetermined noise value. 
     
     
       10. The load driving system of claim 1, wherein the second gear train has motion noise during the connection with the load that is less than the motion noise of the first gear train when connected to the load. 
     
     
       11. The load driving system of claim 10, wherein: the first gear train is comprised of flat gears,   a portion of the second gear train is comprised of helical gears, and   the second pinion gear is a helical gear.   
     
     
       12. The load driving system of claim 10, wherein at least a portion of the second gear train is made of a first material and the first gear train is made of a second material, wherein the first material has a better noise elimination effect than the second material. 
     
     
       13. A load driving system, comprising: a motor;   a first pinion gear installed on a shaft of the motor;   a first gear train for coupling the first pinion gear to a load;   a second pinion gear installed on the shaft of the motor;   a second gear train for coupling the second pinion gear to the load; and   gear train connecting means for connecting the first gear train to the load while the motor is rotating in a first direction and connecting the second gear train to the load while the motor is rotating in a second direction, wherein the second gear train is separated from the load when the first gear train is connected to the load and the first gear train is separated from the load when the second gear train is connected to the load.   
     
     
       14. The load driving system of claim 13, wherein the second gear train has lower motion noise when connected to the load than the first gear train when connected to the load. 
     
     
       15. The load driving system of claim 13, wherein the first gear train is comprised of flat gears and at least a portion of the second gear train is comprised of helical gears. 
     
     
       16. The load driving system of claim 13, wherein at least a portion of the second gear train is made of a first material, the first gear train is made of a second material, and the first material having a better noise elimination effect than the second material. 
     
     
       17. The load driving system of claim 13, wherein the load driving system further comprises: a battery;   battery discharge level detection means for detecting a discharge level of the battery; and   motor control means for causing the motor to rotate in the first direction when the battery discharge level is at least a predetermined value and in the second direction when the battery discharge level is below the predetermined value.   
     
     
       18. A method for driving a load using a motor having first and second rotational directions, and a first pinion gear and a second pinion gear provided on a shaft of the motor, a first gear train having high transmission efficiency and a second gear train having low noise coupling the first and second pinion gears to a load, respectively, the method comprising the steps of: powering the motor using a battery;   detecting a discharge level of the battery; and   selecting one of the first and second gear trains based on the discharge level of the battery.   
     
     
       19. The method of claim 18, wherein the connecting step comprises: separating the second gear train from the load when the first gear train is connected to the load; and   separating the first gear train from the load when the second gear train is connected to the load.   
     
     
       20. The method of claim 18, wherein the selecting step further comprises the steps of: comparing a previous driving speed of the motor with a specified value corresponding to the predetermined value;   selecting the first gear train when the previous driving speed of the motor is below a predetermined value and the second gear train when the previous driving speed of the motor is at least the predetermined value;   measuring a new driving speed of the motor;   storing the measured new driving speed in a memory device as the previous driving speed.   
     
     
       21. The method of claim 20, wherein the selecting step further comprises: rotating the motor in a first direction when the previous driving speed is below a predetermined value to select the first gear train;   rotating the motor in a second direction when the previous driving speed is at least the predetermined value to select the second gear train.